The present invention relates to a recording/reproducing apparatus and a recording/reproducing method, both designed to record and reproduce data on and from a disk-shaped recording medium that has an address data area having embossed pits and a recording/reproducing area having a wobbling spiral groove.
There is known a method of recording address data on an optical disk, in which pits are made in the process of forming the disk, thereby recording the address data. For example, the recording surface of the disk is divided into blocks called “sectors,” each for storing 2048 (2 k) bytes of user data. Header data is recorded, in the form of pits, in the header area of each sector and is used as sector address. A recording/reproducing apparatus first reads the sector address. If the sector address pertains to a desired sector, the apparatus either records data on or reproduces data from the recording/reproducing area that follows the header area.
An optical disk is known, which has a spiral groove made in its surface and wobbling at a specific frequency. A recording/reproducing apparatus reads a wobble signal from the optical disk and reproduces synchronization data from the wobble signal. The amount of the synchronization data is measured in the recording/reproducing apparatus, thereby interpolating the address position, even if the disk has defects, destroying the address data. The apparatus can therefore achieve continuous data-recording. In addition, the frequency of the wobble signal can be used to control the rotation speed of the spindle motor incorporated in the recording/reproducing apparatus.
As described above, the recording/reproducing apparatus generates the synchronization data from the wobble signal and uses the frequency of the wobble signal to control the rotation speed of the spindle motor. The wobble signal must therefore be detected with high precision. It is difficult, however, to detect the wobble signal when a complex operation is performed as the operating mode is switched from the recording mode to the reproducing mode.
The wobble signal may become discontinuous or distorted when a track jump occurs, when the operating mode is switched from the reproducing mode to the recording mode, or when the head crosses the address data area. If this happens, the high-precision synchronization data cannot be generated from the wobble signal.